Gravity return hinge having an axle rod in an axle sleeve

Abstract

An automatic return hinge having a primary and a secondary hinge, the primary hinge being furnished with an axle rod with spiral grooves, three locating balls in an axle sleeve roll along the spiral grooves on the axle rod as the door is opened and closed.

I claim: 
     
       1. An automatic return hinge comprising one primary hinge and one secondary hinge, and said primary hinge including a left side primary hinge piece to be attached to a suitable upper portion of the jamb, and a right side primary hinge piece to be attached to a suitable upper portion of the door, and a locating piece of said right side primary hinge piece being furnished with a sleeve in which an axle sleeve being fitted, and around said axle sleeve, three locating balls being mounted at an equal distance of 120° angle, and in said axle sleeve fitting an axle rod with three slantingly upwards spiral grooves separated at an equal distance of 120° angle so as to match said three locating balls; and at one side of a locating piece of the left side primary hinge piece, having two axle seats with locating grooves in corresponding position; and when the sleeve of said right side primary hinge piece being placed in between the two axle seats of the left side primary hinge piece, the flat ends of the axle rod then being inserted into said locating grooves, and being fixed with screws; and when opening the door moving upwards slightly as a result of the matching function of said spiral grooves and said locating balls, and upon the door opening being over, the door automatically returning to shutting position as a result of door gravity effect. 
     
     
       2. An automatic return hinge as claimed in claim 1, wherein the secondary hinge includes a right side secondary hinge piece to be attached to the lower portion of the door, and a left side secondary hinge piece to be attached to the lower portion of the door, and their shape being the same as that of said left and right side primary hinge pieces; and inside the sleeve nut of said right side secondary hinge piece, installing a steel ball with a thru hole and being so fixed by a sleeve nut that said steel ball having some play for swingingly rotating; and an axle rod being placed inside the steel ball and to be fixed in between the two axle seats of said left side secondary hinge piece, and said axle rod having no spiral groove but by means of the characteristics of swingingly rotating of the steel ball to make universal correction to any deviation of the door. 
     
     
       3. An automatic return hinge as claimed in claim 1, wherein on the back of said locating piece of the left and right side primary and secondary hinge piece, a stub is furnished and is to be placed inside the locating holes of the door and the jamb respectively during installation for positioning purpose. 
     
     
       4. An automatic return hinge as claimed in claim 1, wherein the three spiral grooves on the axle rod are separated at an angle of 120°, having the whole pressure being distributed evenly to the three balls, and each of said grooves having a slantingly ascending angle ranging from 85°-175°; and on the top of each said spiral groove, a suitable length of horizontal groove being extended so as to have the door maintaining in open condition, if necessary, without returning to shutting position automatically as a result of said locating balls having rolled into said horizontal groove. 
     
     
       5. An automatic return hinge as claimed in claim 1, wherein the said left and right side hinge pieces may be designed to have an angle of 90° between them without changing the original functions.